70 OUR BODIES AND HOW WE LIVE 



but little or no food is taken, or if it is not of the right 

 sort, the body slowly loses in weight. If we try to do 

 without food, we grow chilly, feeble, faint, and, after a 

 time, too weak to move. 



THE CLASSIFICATION OF FOODS 



100. Four Great Classes of Food. For convenience we 

 may divide food into four great classes, to which the name 

 food stuffs, or alimentary principles, has been given. 1 



I. Proteids, or nitrogenous foods 



II. Starches and sugars, or carbohydrates 



III. Fats and oils 



IV. Inorganic, or mineral foods 



101. Proteids or Nitrogenous Foods. The proteids, fre- 

 quently spoken of as nitrogenous foods, contain all the mate- 

 rials needed to build up and repair the tissues. They 

 contain nitrogen, carbon, oxygen, and hydrogen, which 

 form the four essential elements of all food. 



The type of this class of foods is egg albumin, familiar 

 as the white of an egg. Lean meat, the cheesy part or 

 curd of milk, peas, and beans are rich in proteids. Wheat, 

 barley, oats, and Indian corn also contain them. 



The proteids are essential food stuffs, as they are neces- 

 sary to life. Without them the tissues of the body would 

 gradually waste away. They supply the material from 



1 To this classification may be added what are called albuminoids, a 

 group of bodies resembling proteids, but having in some respects a different 

 nutritive value. Gelatin, such as is found in soups or table gelatin, is a 

 familiar example of the albuminoids. They are not found to any important 

 extent in our raw foods. 



